Field of the Invention
The present invention relates to a fuel supply system for pressurizing fuel that has flowed inside and supplying the pressurized fuel to an internal combustion engine, and in particular, to a fuel supply system including a pulsation reducing mechanism that reduces pressure pulsation.
Description of the Related Art
A fuel supply system has conventionally been known that moves the proximal end of a plunger into and back from a pressuring chamber formed inside a housing to pressurize fuel having flowed in the pressuring chamber, and supplies the pressurized fuel (hereinafter, referred to as “high pressure fuel”) to an internal combustion engine such as engines (e.g., see Japanese Patent Laid-Open No. 2004-138071).
Such a fuel supply system, which pressurizes fuel by the backward and forward movement of the plunger, causes pulsation in the fuel, and the pulsation may propagate to a channel area having pressure lower than the pressure of the pressuring chamber, resulting in damage to the lower pressure area of the channel. Thus, providing a pulsation damper mechanism for reducing the pulsation has also been known.
For example, the fuel supply system described in Patent Laid-Open No. 2004-138071 provides a tubular space (hereinafter, referred to as “tubular chamber”) around the pressuring chamber, and the edge of a metal thin layer is welded on the wall surface of the tubular chamber as a diaphragm. The volume of the space between the diaphragm and the wall surface of the tubular chamber is varied to reduce pulsation.
However, the tubular chamber of the conventional fuel supply system has a small internal space, and thus the work of providing the diaphragm by welding the metal thin layer onto the wall surface of the tubular chamber is troublesome, resulting in a problem of deteriorated assembly.
Furthermore, the small internal space of the tubular chamber in the conventional fuel supply system causes the positioning of the diaphragm to be formed (i.e., determining the arrangement position of the pulsation reducing mechanism) to be difficult, and thus the arrangement position of the pulsation reducing mechanism may shift from the position that allows pulsation occurring by the plunger reciprocating motion to be sufficiently reduced. As a result, the pulsation reducing function may be insufficient.
The present invention has been made in view of such circumstances. An object of the present invention is to provide a fuel supply system that allows improved assembly and pulsation reducing efficiency.